The present invention relates to a CVD (chemical Vapor Deposition) apparatus and a CVD method, and more particularly, a CVD apparatus and a CVD method for forming an Al/Cu multilayered film.
In a semiconductor device, wiring (e.g., metal) is generally formed on a device formation region on a silicon semiconductor wafer by, for example, etching an Alxe2x80x94Cu film formed by sputtering using an Al-0.5 wt % Cu-target.
Recently, with the trend toward high integration of the semiconductor device, it has been desired to reduce the wiring width. However, it is difficult for a hitherto-used sputtering method to form a fine wiring which will be required by a design rule in future.
Then, as a technique replaceable for the sputtering method, a CVD method has been studied. Since the CVD method includes a vapor deposition step, a film is easily formed on a complicated substrate surface and minute portions such as portions having a large aspect ratio and contact holes.
However, it is difficult to form the Alxe2x80x94Cu film suitable for wiring by the CVD method.
To form the Alxe2x80x94Cu film, conventionally employed is a method in which a Cu component is added to an Al film (CVD) formed by the CVD method. In the conventional method, the Cu component is diffused into the Al film (CVD) by depositing an Alxe2x80x94Cu film or a Cu film on the Al film (CVD) by sputtering and annealing the obtained film.
The Alxe2x80x94Cu film of this type is reported in xe2x80x9cSymposium on VLSI technology Digest of Technical Papers (1996), p42xe2x80x9d.
In the case where the Cu component is dispersed into the Al film (CVD) by use of a single wafer process system having a multichamber type, two process chambers are required; one is to form the Al film by the CVD method and the other is to form the Alxe2x80x94Cu film or the Cu film by sputtering. However, film-formation has to be performed two times by transporting a single wafer between two process chambers. As a result, the throughput thereof inevitably decreases.
To overcome the decrease in throughput, if a plurality of chambers are prepared for each of the Al-film formation and Alxe2x80x94Cu film or the Cu film formation, the entire apparatus becomes quite large, raising a manufacturing cost.
An object of the present invention is to provide a CVD apparatus and a CVD method capable of obtaining an Al/Cu multilayered film with a high throughput but without increasing the size of the apparatus.
The present invention provides a CVD (chemical vapor deposition) apparatus comprising:
a chamber capable of maintaining vacuum conditions having an exhausting system;
a susceptor disposed in the chamber, for mounting an object to be processed;
an Al raw material supply system having a first passage for introducing a gasified Al raw material into the chamber, for forming an Al film;
a Cu raw material supply system having a second passage for introducing a gasified Cu raw material into the chamber, for forming a Cu film, the first passage being independent of the second passage; and
exhausting means for vacuum-exhausting a gas including the gasified raw material introduced into the chamber;
wherein the Al film (formed of the Al raw material gas) and the Cu film (formed of the Cu raw material gas) are alternately stacked one upon the other by chemical vapor deposition (CVD) on a surface of the object to be processed by introducing the Al raw material gas or the Cu raw material gas alternately.
The Al raw material supply system of the CVD apparatus comprises an Al raw material supply line for supplying an Al raw material. The Al raw material supply line includes:
Al raw material gas generating means for generating a predetermined amount of an Al raw material gas from a liquid-state Al raw material contained in a vessel by bubbling with a predetermined carrier gas or direct gasification;
Al gas bypass means for either supplying the generated Al raw material gas to the Al raw material supply system or exhausting the generated Al raw material gas outside using the exhausting means by switch operation of a valve;
first gas purge means for purging a remaining gas in the chamber or in a gas pipe by supplying a predetermined carrier gas either from the Al raw material gas supply line to the chamber or from the Al raw material supply line to the Al raw material gas bypass means; and
Al raw material switching means for switching either between the Al raw material gas bypass means and the Al raw material supply line or between the first gas purge means and the Al raw material supply line.
The Cu raw material supply system comprises a Cu raw material supply line for supplying a Cu raw material.
The Cu raw material supply line includes
Cu raw material gas generating means for generating a predetermined amount of a Cu raw material gas gasified by heating a solid-state Cu raw material contained in a vessel with the aid of a predetermined carrier gas;
Cu gas bypass means for either supplying the generated Cu raw material gas to the Cu raw material supply system or exhausting the generated Cu raw material gas outside using the exhausting means by switch operation of a valve;
second gas purge means for purging a remaining gas in the chamber or in a gas pipe by supplying a predetermined carrier gas either from the Cu raw material gas supply line to the chamber or from the Cu raw material supply line to the Cu raw material gas bypass means; and
Cu raw material switching means for switching either between the Cu raw material gas bypass means and the Cu raw material supply line or between the second gas purge means and the Cu raw material supply line.
The present invention further provides a CVD method of forming a film from the raw material on a surface of an object to be processed which is placed in an atmosphere mainly consisting of a predetermined raw material gas. The CVD method comprises:
a multilayered film formation step for forming an Al/Cu multilayered film by repeating, predetermined times, Al film formation for forming an Al film on a surface of the object to be processed by introducing a gasified Al raw material (Al raw material gas) into the atmosphere and Cu film formation for forming a Cu film on a surface of the object to be processed by introducing a gasified Cu raw material (Cu raw material gas) into the atmosphere, thereby forming an Al/Cu multilayered film in which the Al film and the Cu film are stacked alternately on the object to be processed surface; and
a heat treatment step for annealing the Al/Cu multilayered film under predetermined conditions, thereby forming a desired Al/Cu alloy film in which diffusion between the Al film and the Cu film takes place.
As mentioned in the foregoing, the present invention provides a CVD apparatus and a CVD method for use in forming an Al/Cu multilayered film. The Al/Cu multilayered film is formed in the CVD apparatus comprising a chamber for placing an object to be processed, a susceptor for mounting the object to be processed thereon, an Al raw material supply system for introducing a gasified Al raw material into the chamber and a Cu raw material supply system for introducing a gasified Cu raw material into the chamber. The Al/Cu multilayered film is formed by repeating a series of steps consisting of introducing the Al raw material gas into the chamber, depositing the Al film on the object to be processed by a CVD method, followed by introducing the Cu raw material gas into the chamber and depositing the Cu film on the object to be processed by a CVD method. The Al/Cu multilayered film thus obtained is subjected to a heating treatment (annealing), thereby forming a desired Al/Cu multilayered film.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinbefore.